The invention relates to a subscriber set comprising two line terminals, a hook switch and an electronic telephone set circuit.
Such a subscriber set is known, for example, from the Philips Data Handbook "IC's for Telecom Subscriber Sets, Cordless Telephones, Mobile/Cellular Radio Pagers CA 3089 to PCD 4413", Book IC03a, 1991.
On page 851 of this handbook a block diagram of such a subscriber set is shown comprising terminals a/b, b/a for connecting the subscriber set to a transmission line, for example, a telephone line. The subscriber set comprises an electronic telephone set circuit which includes, for example, a transmission circuit TEA 1060, a dedicated microcontroller PCD 3349, drivers such as the PCF 8576 and a RAM such as the PCF 8571.
This telephone set circuit is connected in customary fashion to the line terminals by way of a rectifier circuit and a hook switch. This hook switch is a mechanical switch or a relay through which the line current flows coming from the subscriber line. This means that the hook switch is arranged for switching a power equal to the maximum line current occurring in very short subscriber lines, and the associated DC line voltage increased by the ringing signal power. Such a hook switch is relatively expensive for modem telephone sets.